🚀 ExamNotesAI – AI Powered Credit-Based SaaS Platform

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🌟 Overview

ExamNotesAI is a production-style AI-powered SaaS web application that allows users to generate smart exam notes using AI and purchase usage credits securely via Stripe.

This project demonstrates real-world backend architecture including secure authentication, payment gateway integration, webhook verification, and a credit-based transaction system.

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🎯 Key Highlights

✔ Implemented secure Google OAuth authentication using Firebase
✔ Designed JWT-protected backend architecture
✔ Integrated Stripe Checkout with webhook verification
✔ Built a credit-based payment system using Stripe metadata validation
✔ Integrated Google Gemini AI API for intelligent note generation
✔ Connected MongoDB Atlas for scalable cloud database storage
✔ Managed environment variables securely
✔ Designed SaaS-style backend architecture

This reflects real startup-level SaaS backend implementation.

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🏗 Tech Stack

🔹 Frontend

• React (Vite)
• Firebase Authentication
• Axios

🔹 Backend

• Node.js
• Express.js
• MongoDB Atlas (Mongoose ODM)
• JWT Authentication
• Stripe API + Webhooks
• Google Gemini API

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📂 Project Structure

ExamNotesAI/
│
├── client/          → React Frontend
├── server/          → Node + Express Backend
├── README.md
└── .gitignore

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⚙️ Local Setup Guide

1️⃣ Clone Repository

git clone https://github.com/rajratan-rajput/ExamNotesAI.git
cd ExamNotesAI

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2️⃣ Backend Setup

cd server
npm install

Create server/.env

PORT=8000
MONGODB_URL=your_mongodb_connection_string
JWT_SECRET=your_secret_key
GEMINI_API_KEY=your_gemini_api_key
STRIPE_SECRET_KEY=sk_test_...
STRIPE_WEBHOOK_SECRET=whsec_...
CLIENT_URL=http://localhost:5173

Run backend:

npm run dev

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3️⃣ Frontend Setup

cd client
npm install

Create client/.env

VITE_FIREBASE_APIKEY=your_firebase_api_key

Run frontend:

npm run dev

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💳 Stripe Webhook Setup (Local Testing)

Login Stripe CLI:

stripe login

Start webhook listener:

stripe listen --forward-to localhost:8000/api/credits/webhook

Copy the whsec_ key into backend .env.

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🧪 Stripe Test Payment Card

4242 4242 4242 4242
Any future date
Any 3-digit CVC
Any 5-digit ZIP

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🚀 Deployment Guide

🔹 Backend Deployment (Render / Railway)

1. Push repository to GitHub
2. Connect repository to Render
3. Add environment variables in dashboard
4. Build command:

npm install

5. Start command:

node index.js

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🔹 Frontend Deployment (Vercel / Netlify)

1. Connect GitHub repository
2. Build command:

npm run build

3. Output directory:

dist

4. Add environment variable:

VITE_FIREBASE_APIKEY

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🔐 Security Features

• Stripe webhook signature verification
• JWT-protected routes
• Metadata-based secure credit allocation
• Environment-based secret management
• No sensitive keys exposed in frontend

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📈 Future Improvements

• Idempotent webhook handling
• Payment transaction history logging
• Subscription-based billing
• Role-based access control
• Production Stripe live mode integration
• Cloud deployment optimization

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👨‍💻 Author

Rajratan Rajput
GitHub: https://github.com/rajratan-rajput

Full Stack Developer | MERN Stack | Backend Engineering

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